Fenestration comes from the Latin word fenestra meaning window.

It refers to the design, proportion, and arrangement of windows, doors, skylights, and other openings in the walls of a building.

Fenestration is critical for:

• Natural light and ventilation
• Thermal performance (heat gain/loss)
• Visual aesthetics and facade composition
• Views and connection to the exterior

It is a major component of building envelope design and energy efficiency.